The Experts below are selected from a list of 108903 Experts worldwide ranked by ideXlab platform
Yves F Dufrene - One of the best experts on this subject based on the ideXlab platform.
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the importance of force in Microbial Cell adhesion
Current Opinion in Colloid and Interface Science, 2020Co-Authors: Sofiane Elkiratchatel, Audrey Beaussart, Marion Mathelieguinlet, Yves F DufreneAbstract:Abstract Microbes have evolved sophisticated strategies to colonize biotic and abiotic surfaces. Forces play a central role in Microbial Cell adhesion processes, yet until recently these were not accessible to study at the molecular scale. Unlike traditional assays, atomic force microscopy (AFM) is capable to study forces in single Cell surface molecules and appendages, in their biologically relevant conformation and environment. Recent AFM investigations have demonstrated that bacterial pili exhibit a variety of mechanical responses upon contact with surfaces and that Cell surface adhesion proteins behave as force-sensitive switches, two phenomena that play critical roles in Cell adhesion and biofilm formation. AFM has also enabled to assess the efficiency of sugars, peptides, and antibodies in blocking Cell adhesion, opening up new avenues for the development of antiadhesion therapies against pathogens.
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sticky microbes forces in Microbial Cell adhesion
Trends in Microbiology, 2015Co-Authors: Yves F DufreneAbstract:Understanding the fundamental forces involved in the adhesion of Microbial Cells is important not only in microbiology, to elucidate Cellular functions (such as ligand-binding or biofilm formation), but also in medicine (biofilm infections) and biotechnology (Cell aggregation). Rapid progress in atomic force microscopy (AFM) techniques has made it possible to measure the forces driving Cell–Cell and Cell–substrate interactions on a single Cell basis. A living Cell is attached to the AFM probe, thereby enabling researchers to measure the interaction forces between the Cell and a target surface. Recent advances in our understanding of the forces driving Cell adhesion and biofilm formation are discussed, with a focus on pathogens. These studies provide compelling evidence that, upon contact with a surface, Cell adhesion components display a variety of mechanical responses that are important for Cell adhesion.
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quantifying the forces guiding Microbial Cell adhesion using single Cell force spectroscopy
Nature Protocols, 2014Co-Authors: Audrey Beaussart, Sofiane Elkiratchatel, Ruby May A Sullan, David Alsteens, Philippe Herman, Sylvie Derclaye, Yves F DufreneAbstract:During the past decades, several methods (e.g., electron microscopy, flow chamber experiments, surface chemical analysis, surface charge and surface hydrophobicity measurements) have been developed to investigate the mechanisms controlling the adhesion of Microbial Cells to other Cells and to various other substrates. However, none of the traditional approaches are capable of looking at adhesion forces at the single-Cell level. In recent years, atomic force microscopy (AFM) has been instrumental in measuring the forces driving Microbial adhesion on a single-Cell basis. The method, known as single-Cell force spectroscopy (SCFS), consists of immobilizing a single living Cell on an AFM cantilever and measuring the interaction forces between the Cellular probe and a solid substrate or another Cell. Here we present SCFS protocols that we have developed for quantifying the Cell adhesion forces of medically important microbes. Although we focus mainly on the probiotic bacterium Lactobacillus plantarum, we also show that our procedures are applicable to pathogens, such as the bacterium Staphylococcus epidermidis and the yeast Candida albicans. For well-trained microscopists, the entire protocol can be mastered in 1 week.
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atomic force microscopy probing the spatial organization interactions and elasticity of Microbial Cell envelopes at molecular resolution
Molecular Microbiology, 2010Co-Authors: Simon Scheuring, Yves F DufreneAbstract:P>Although much is known about the structure and biosynthesis of Microbial Cell envelope constituents, the three-dimensional organization, assembly and interactions of the individual components remain poorly understood. How do Cell walls remodel during Cell growth or incubation with drugs? What is the supramolecular architecture of proteins in bacterial surface layers, in outer membranes and in intracytoplasmic membranes? What is the spatial arrangement of Cell surface receptors, clustered or homogeneous? What are the adhesive and mechanical properties of Cell surface proteins and how are they related to function? Traditionally, these questions have been difficult - or impossible - to address owing to the lack of high-resolution single-Cell and single-molecule probing techniques. With its ability to observe and force probe the Cell envelope down to the molecular level under physiological conditions, atomic force microscopy (AFM) has recently offered new opportunities in molecular microbiology. While high-resolution AFM imaging is a powerful tool for visualizing the architecture of Cells and membranes in buffer solution, force spectroscopy offers a means to analyse the localization, interactions and elasticity of their individual constituents. These nanoscale experiments complement microscopy, genetics and biochemical methods traditionally used to analyse the Microbial envelope.
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atomic force microscopy a powerful tool in microbiology
Journal of Bacteriology, 2002Co-Authors: Yves F DufreneAbstract:Understanding the functions of Microbial Cell surfaces requires knowledge of their structural and physical properties. Electron microscopy has long been recognized as a key technique in microbiology to elucidate Cell surface ultrastructure ([6][1], [7][2], [44][3], [45][4]). An exciting achievement
Henk J. Busscher - One of the best experts on this subject based on the ideXlab platform.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV-light, extreme pH-values and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors and human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a “super-bug”, resistant to all known antiMicrobial measures doesnot exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron-microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform-infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms and X-ray diffraction. It is amazing that X-ray-Photoelectron-Spectroscopy (XPS) is forgotten as a method to characterize encapsulated microorganisms. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic-acid, peptidoglycan and hydrocarbon-like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, it has seldom or never been applied to characterize the different types of surface-engineered shells around yeasts and bacteria currently described in literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for the protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV light, extreme pH values, and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors, and the human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a "super-bug," resistant to all known antiMicrobial measures does not exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms, and X-ray diffraction. It is amazing that X-ray Photoelectron Spectroscopy (XPS) is forgotten as a method to characterize encapsulated yeasts and bacteria. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be easily pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into well-known, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic acid, peptidoglycan, and hydrocarbon like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, XPS has seldom been applied to characterize the many different types of surface-engineered shells around yeasts and bacteria currently described in the literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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electrophoretic mobility distributions of single strain Microbial populations
Applied and Environmental Microbiology, 2001Co-Authors: Henny C Van Der Mei, Henk J. BusscherAbstract:Microbial Cell surface hydrophobicity ([15][1], [19][2]) is probably the most studied Microbial Cell surface characteristic measured due to its ubiquitously accepted role in Microbial adhesion to surfaces ([1][3], [20][4],[23][5]). Yet, the electrostatic charge properties of Microbial Cell surfaces
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Microbial Cell surface hydrophobicity the involvement of electrostatic interactions in Microbial adhesion to hydrocarbons math
Journal of Microbiological Methods, 1993Co-Authors: G I Geertsemadoornbusch, Van Der Henny C Mei, Henk J. BusscherAbstract:Abstract Microbial adhesion to hydrocarbons (MATH) is the most commonly used method to determine Microbial Cell surface hydrophobicity. Since, however, the assay is based on adhesion, it is questionable whether the results reflect only the Cell surface hydrophobicity or an interplay of hydrophobicity and surface charge properties. In order to demonstrate the involvement of electrostatic interactions in MATH hydrophobicities by MATH (kinetic mode) were measured in 10 mM potassium phosphate solutions at different pH's and compared with the zeta potentials of the microorganisms and of hexadecane droplets in the same solution. Two oral, Microbial strains were involved: Streptococcus salivarius HB (a hydrophobic strain by MATH) and Streptococcus salivarius HB-C12 (a hydrophilic strain by MATH). The initial removal rates of S. salivarius HB-C12 by hexadecane were zero over the entire pH range (pH 2-pH 9) and its zeta potentials were negative in this pH range. S. salivarius HB, however, had an isoelectric point (IEP) at pH 3.2 and accordingly a positive zeta potential below IEP. Correspondingly, the initial removal rates found for this strain were high (2.6 min−1) below and around IEP and much lower (∽ 0.5 min−1) above IEP. Surprisingly, the hexadane droplets also had highly negative zeta potentials above pH 4 and appeared uncharged in the pH range 2–3. Taking the product of the bacterial δb and hexadecane δh zeta potentials as a measure for electrostatic interactions, it was observed that the measured hydrophobicity of S. salivarius HB, but nut of the hydrophilic strain S. salivarius HB-C12, depended on electrostatic interactions as well. The highest removal rates by hexadecane were found in the absence of electrostatic interactions, i.e. in the pH range close to the IEP's of the interacting particles. It is concluded that, in general, MATH does not measure Cell surface hydrophobicity but an interplay of hydrophobicity and electrostatic interactions. The involvement of electrostatoc interactions in MATH can be reduced by performing the test under ionic conditions in which either the Cells or the hydrocarbon droplets (or both) are uncharged.
Xiaoyu Yang - One of the best experts on this subject based on the ideXlab platform.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV-light, extreme pH-values and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors and human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a “super-bug”, resistant to all known antiMicrobial measures doesnot exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron-microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform-infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms and X-ray diffraction. It is amazing that X-ray-Photoelectron-Spectroscopy (XPS) is forgotten as a method to characterize encapsulated microorganisms. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic-acid, peptidoglycan and hydrocarbon-like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, it has seldom or never been applied to characterize the different types of surface-engineered shells around yeasts and bacteria currently described in literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for the protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV light, extreme pH values, and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors, and the human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a "super-bug," resistant to all known antiMicrobial measures does not exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms, and X-ray diffraction. It is amazing that X-ray Photoelectron Spectroscopy (XPS) is forgotten as a method to characterize encapsulated yeasts and bacteria. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be easily pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into well-known, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic acid, peptidoglycan, and hydrocarbon like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, XPS has seldom been applied to characterize the many different types of surface-engineered shells around yeasts and bacteria currently described in the literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
Henny C Van Der Mei - One of the best experts on this subject based on the ideXlab platform.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for the protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV light, extreme pH values, and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors, and the human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a "super-bug," resistant to all known antiMicrobial measures does not exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms, and X-ray diffraction. It is amazing that X-ray Photoelectron Spectroscopy (XPS) is forgotten as a method to characterize encapsulated yeasts and bacteria. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be easily pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into well-known, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic acid, peptidoglycan, and hydrocarbon like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, XPS has seldom been applied to characterize the many different types of surface-engineered shells around yeasts and bacteria currently described in the literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV-light, extreme pH-values and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors and human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a “super-bug”, resistant to all known antiMicrobial measures doesnot exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron-microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform-infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms and X-ray diffraction. It is amazing that X-ray-Photoelectron-Spectroscopy (XPS) is forgotten as a method to characterize encapsulated microorganisms. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic-acid, peptidoglycan and hydrocarbon-like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, it has seldom or never been applied to characterize the different types of surface-engineered shells around yeasts and bacteria currently described in literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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electrophoretic mobility distributions of single strain Microbial populations
Applied and Environmental Microbiology, 2001Co-Authors: Henny C Van Der Mei, Henk J. BusscherAbstract:Microbial Cell surface hydrophobicity ([15][1], [19][2]) is probably the most studied Microbial Cell surface characteristic measured due to its ubiquitously accepted role in Microbial adhesion to surfaces ([1][3], [20][4],[23][5]). Yet, the electrostatic charge properties of Microbial Cell surfaces
Hao Wei - One of the best experts on this subject based on the ideXlab platform.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV-light, extreme pH-values and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors and human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a “super-bug”, resistant to all known antiMicrobial measures doesnot exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron-microscopy, energy-dispersive X-ray spectroscopy, Fourier-transform-infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms and X-ray diffraction. It is amazing that X-ray-Photoelectron-Spectroscopy (XPS) is forgotten as a method to characterize encapsulated microorganisms. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic-acid, peptidoglycan and hydrocarbon-like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, it has seldom or never been applied to characterize the different types of surface-engineered shells around yeasts and bacteria currently described in literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.
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x ray photoelectron spectroscopy on Microbial Cell surfaces a forgotten method for the characterization of microorganisms encapsulated with surface engineered shells
Frontiers in Chemistry, 2021Co-Authors: Hao Wei, Henny C Van Der Mei, Xiaoyu Yang, Henk J. BusscherAbstract:Encapsulation of single Microbial Cells by surface-engineered shells has great potential for the protection of yeasts and bacteria against harsh environmental conditions, such as elevated temperatures, UV light, extreme pH values, and antiMicrobials. Encapsulation with functionalized shells can also alter the surface characteristics of Cells in a way that can make them more suitable to perform their function in complex environments, including bio-reactors, bio-fuel production, biosensors, and the human body. Surface-engineered shells bear as an advantage above genetically-engineered microorganisms that the protection and functionalization added are temporary and disappear upon Microbial growth, ultimately breaking a shell. Therewith, the danger of creating a "super-bug," resistant to all known antiMicrobial measures does not exist for surface-engineered shells. Encapsulating shells around single microorganisms are predominantly characterized by electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, particulate micro-electrophoresis, nitrogen adsorption-desorption isotherms, and X-ray diffraction. It is amazing that X-ray Photoelectron Spectroscopy (XPS) is forgotten as a method to characterize encapsulated yeasts and bacteria. XPS was introduced several decades ago to characterize the elemental composition of Microbial Cell surfaces. Microbial sample preparation requires freeze-drying which leaves microorganisms intact. Freeze-dried microorganisms form a powder that can be easily pressed in small cups, suitable for insertion in the high vacuum of an XPS machine and obtaining high resolution spectra. Typically, XPS measures carbon, nitrogen, oxygen and phosphorus as the most common elements in Microbial Cell surfaces. Models exist to transform these compositions into well-known, biochemical Cell surface components, including proteins, polysaccharides, chitin, glucan, teichoic acid, peptidoglycan, and hydrocarbon like components. Moreover, elemental surface compositions of many different Microbial strains and species in freeze-dried conditions, related with zeta potentials of Microbial Cells, measured in a hydrated state. Relationships between elemental surface compositions measured using XPS in vacuum with characteristics measured in a hydrated state have been taken as a validation of Microbial Cell surface XPS. Despite the merits of Microbial Cell surface XPS, XPS has seldom been applied to characterize the many different types of surface-engineered shells around yeasts and bacteria currently described in the literature. In this review, we aim to advocate the use of XPS as a forgotten method for Microbial Cell surface characterization, for use on surface-engineered shells encapsulating microorganisms.